Sound Post Diameter

[reedo35]

Quick question for all those Luthier types and sound afficionados out there. How much does the sound post diameter affect the Bass? Is it supposed to be proportionate to the size of the Bass? Will a thicker sound post make the instrument resonate deeper, and a thinner one give a brighter sound? And what about supporting the top? Will it cause it to vibrate differently?

[Silversorcerer]

Do some experiments and let us know what you find out. The bigger the bass the large diameter the post, but it doesn't vary more than a mm or 2. Position of the post is usually how the post is adjusted to change the sound of the bass. The proper post diameter might be more of a mechanical consideration. There are standard post diameters for 3/4, 4/4, and other size instruments.

[Bob Branstetter]

In the violin (family) world, soundposts seem to draw more attention that almost any other part of the instrument. Study after study has tried and tested just about every alteration possible and patents have been given to many for different designs. But IMO, as long as the soundposts are fitted properly, I personally don't think that soundpost diameter is going to make much difference in the sound within the practical limits of what can be removed and set through the ff holes.

Unlike most violin makers, most double bass luthiers buy soundpost blanks from suppliers rather than make their own. Diameters normally fall in the 16-19mm range and most commercial soundpost blanks are made of a medium density European spruce. However, I've been making my own soundpost blanks for about 30 years. It has been my experience that most carved top basses sound best with soft to medium density spruce soundpost. Many times, an overly dark sounding bass can be made brighter with a harder post. However, there are limits. I once made a batch of soundpost blanks from some Alaskan Sitka Spruce that had been under saltwater for over 25 years before being recovered. For some reason, this batch of spruce is the hardest spruce I've ever seen and I've never found a (carved) bass that sounds good with these. Plywood basses are a different animal when it comes to sound posts. Many of these actually sound better with a hard soundpost. The original Kay soundposts were maple. I've replaced a few Kays with softer spruce posts and they did not sound as good as they did with the original maple soundpost. Chuck Traeger mentions this phenomenon in his book.

[mojoluthier]

I have thot of the Kay posts slotted their length as being the original equipmet, but haven't noticed any in maple; all spruce! The weight alone should tip me, I'll pay close attention next one thru.

I make my own sound posts, but do not consider myself expert enough to add much to this topic. In fact I hope to learn something. Many basses have too small an ff hole to accept bigger than 3/4 inch thru the slot. I use Adirondack Spruce mostly (it's what I have) and 11/16 feels right to me. Why go bigger than necessary as it just adds weight where you probably want it least?

[Mark Carlsen]

Bob...How can you even try to say that original Kay soundposts are Maple? Looks like domestic spruce to me,although you are the Master of All Things Bass, so I guess I am wrong from the get go... {I only have 6 Kays in the shop from a 49 M-1 to an Orchestra Model w. a 2400 serial number} My real guess is it's Fir [Little Hairs] or Hickory...

[Bob Branstetter]

Originally Posted by Mark Carlsen

Bob...How can you even try to say that original Kay soundposts are Maple? Looks like domestic spruce to me,although you are the Master of All Things Bass, so I guess I am wrong from the get go... {I only have 6 Kays in the shop from a 49 M-1 to an Orchestra Model w. a 2400 serial number} My real guess is it's Fir [Little Hairs] or Hickory...

OK Mark, I must be wrong. SIUYA

[Mark Carlsen]

Originally Posted by Bob Branstetter

OK Mark, I must be wrong. SIUYA

Wow, Bob...How did you know I just had a Colonoscopy We're you peekin....

[Bob Branstetter]

Originally Posted by Mark Carlsen

Wow, Bob...How did you know I just had a Colonoscopy We're you peekin....

I was tempted to take this to the next level, but I imagine that most people here have figured out that I don't like you and you don't like me. I'll leave it at that.

[Mark Carlsen]

TBTTH

[Martin Sheridan]

Here's something I do with both soundposts and bridges, but only for the best basses. There are "fast" posts and bridges and "slow" posts and bridges. What I mean by this is that if you take five posts in hand and give each one of them a short toss onto the floor or workbench they will bounce. I like the ones that dance around the most. To me it means they vibrate more. Sometimes I toss them more than once and narrow down to lets say two posts and then compare them several times. It may mean nothing at all, but I like the bridges and posts that hop, skip, and jump around the most.

I recently received two posts that were only 16mm in diameter. It seems like they usually send the 19mm ones. I tried one of them in my new bass and it really responds. Is it the post or the bass? Who knows.

[Bob Branstetter]

Originally Posted by Martin Sheridan

I recently received two posts that were only 16mm in ost.diameter. It seems like they usually send the 19mm ones. I tried one of them in my new bass and it really responds. Is it the post or the bass? Who knows.

Unless you want to go to the effort of fitting one of the 19mm posts (and then finding it results in less response), I would be inclined to give most of the credit to the maker instead of the soundpost diameter. I assume that your supplier sent you 16mm posts that were made from the same wood species and density as the 19mm posts previously sent.

BTW, did you ever have the opportunity to try any of the 19mm posts that I made for Misha and Anton Krutz? They were made from a log of the BC spruce they got from Old Standard.

[Martin Sheridan]

Originally Posted by Bob Branstetter

BTW, did you ever have the opportunity to try any of the 19mm posts that I made for Misha and Anton Krutz? They were made from a log of the BC spruce they got from Old Standard.

No Bob, not that I know of. Did you buy it or did they? By the time I was there, I don't think they were buying much from the guys at Old Standard Wood anymore. John and Ben had some really good wood. I used some of their wood on my last cello. They may be back buying from them again because they didn't have any arguments with the quality, I think they just got a good deal on some wood from Alaska and had someone drive up there and get it, but that's been a few years ago.
They bought an entire cargo container from Russia once, but the wood wasn't good enough to use for anything but experimenting and construction!

[Bob Branstetter]

Originally Posted by Martin Sheridan

No Bob, not that I know of. Did you buy it or did they? By the time I was there, I don't think they were buying much from the guys at Old Standard Wood anymore. John and Ben had some really good wood. I used some of their wood on my last cello. They may be back buying from them again because they didn't have any arguments with the quality, I think they just got a good deal on some wood from Alaska and had someone drive up there and get it, but that's been a few years ago.
They bought an entire cargo container from Russia once, but the wood wasn't good enough to use for anything but experimenting and construction!

It was a just small log that was sitting on the floor of their other building. They bought it and Anton gave me the wood to use. I think I made 50 for them and I kept 50. Anton told me about that Russian wood and he was not a happy camper. Sounds like they pulled a bait and switch on him quality wise. I wonder if the Alaskan wood was from Larry Trumble at Wood Marine. I bought a dozen Sitka tops from him about 15 years ago and it was great wood although I did have to dry it myself for several years before I could use it.

[Anonymous75966]

Anyone ever seen the "TK 92" in person? Very unusual bass by Thomas Kelischek that was featured in Double Bassist #3. Among its features:

Originally Posted by John Chiego

Even the soundpost has been altered to Keslichek's visionary version of the double bass. It is twice the diameter of a conventional soundpost. By widening it, Kelischek felt he would give extra support to the top of the instrument and distribute the force the soundpost exerts over a far wider area. The fatter post gives the bass a somewhat less strident sound which is often a shortcoming of new instruments. However, Kelischek cut six different posts for the TK '92 - two fat ones and four conventional ones - anticipating that a more projecting tone would often be desired for solo playing.

Damn my trivia brain ...

[reedo35]

Yes, I am familiar with that Bass. That's only one of the reasons I asked this question. This discussion has been interesting so far...

[Silversorcerer]

Originally Posted by Martin Sheridan

Here's something I do with both soundposts and bridges, but only for the best basses. There are "fast" posts and bridges and "slow" posts and bridges. What I mean by this is that if you take five posts in hand and give each one of them a short toss onto the floor or workbench they will bounce. I like the ones that dance around the most. To me it means they vibrate more. Sometimes I toss them more than once and narrow down to lets say two posts and then compare them several times. It may mean nothing at all, but I like the bridges and posts that hop, skip, and jump around the most.

I recently received two posts that were only 16mm in diameter. It seems like they usually send the 19mm ones. I tried one of them in my new bass and it really responds. Is it the post or the bass? Who knows.

One day when I was in Emile Baran's shop in Decatur, he was dropping sound posts on the floor, which was hard tile. I was not quite sure what was going on. I guess that explains it.

[Martin Sheridan]

I forgot to say that I listen to them to. The ones that dance the best also seem to have the loudest and clearest ping.